Color photographic materials processed in the presence of anti-color fogging agents

ABSTRACT

A process for the production of colored images by chromogenic processing of color photographic materials with at least one silver halide emulsion layer wherein the material is processed in the presence of at least one 2-propinylthioderivative which are able to reduce the formation of color fogs.

United States Patent [191 Lohmer et al.

[ Oct. 7, 1975 COLOR PHOTOGRAPHIC MATERIALS PROCESSED IN THE PRESENCE OF ANTI-COLOR FOGGlNG AGENTS [75] Inventors: Karl Lohmer; Anita von Kiinig, both of Leverkusen; Anneliese Miiller, Cologne, all of Germany [73] Assignee: Agfa-Gevaert Aktiengesellschaft,

Leverkusen-Bayerwerk, Germany 22 Filed: Jan. 25, 1974 211 Appl. No.: 436,477

[30] Foreign Application Priority Data Jan. 30, 1973 Germany 2304321 [52] US. Cl 96/56; 96/61 R; 96/62; 96/66.5; 96/100; 96/109 [51] Int. Cl. G03C 7/00 Primary Examiner-J. Travis Brown Attorney, Agent, or Firm-Connolly and Hutz ABSTRACT A process for the production of colored images by chromogenic processing of color photographic materials with at least one silver halide emulsion layer wherein the material is processed in the presence of at least one 2-propinylthioderivative which are able to reduce the formation of color fogs.

7 Claims, No Drawings COLOR PHOTOGRAPHIC MATERIALS PROCESSED IN THE PRESENCE OF ANTI-COLOR FOGGING AGENTS This invention relates to anti-color-fogging agents for color photographic recording materials, and to a process for stabilizing color photographic materials by the addition of suitable anti-color-fogging agents which are able to reduce the formation of color fogs.

Colored images are produced in known manner by developing exposed silver halide emulsions in the presence of conventional color developers, a colored image being produced in addition to the silver image through reaction of the oxidized color developer with color couplers simultaneously present. The color couplers can be added in known manner either to the emulsion layers, to the adjacent layers or to the developer solution. In particular, p-phenylene diamines or their substituted derivatives are normally used as color developers for producing colored images.

The colored images obtained by the conventional processes often shown colo'r fogging or discoloration. The formation of a color fog may be attributed to the fact that the developer compounds are oxidized to a certain degree under the action of air, and to the fact that the oxidized developer has a tendency to couple with the color coupler at those places in the photographic recording material in which no silver image has originally been produced. This troublesome oxidation of the developer can be caused by the influence of air or by additives present in the emulsions and can occur uniformly in the individual layers or to a greater extent in one or more layers, resulting either in a uniform color fog or in discoloration of the photographic material. This effect is particularly noticeable in recording materials of the kind which contain couplers incorporated into the photosensitive layers and, especially, in cases where developer solutions which have not been sufficiently stabilized against oxidation are used. The color fog or the discoloration cannot be prevented by the processes commonly used for stabilizing the silver fog.

US. Pat. No. 2,403,721 and 2,701,197 and German Offenlegungsschrift No. 2,1 l0,52l propose the use of alkyl and dialkyl hydroquinone derivatives as anticolor-fogging agents for color photographic materials.

One disadvantage of these compounds, however, is that many of them are extremely difficult to produce, even by processes involving 2 to 4 stages. Another disblesome secondary products discolor the photographic material, which is a disadvantage especially with color photographic copying materials.

It is also known that color reproduction can be im- 5 proved by arranging, between the photosensitive silver halide emulsion layer and a layer containing the color couplers, an intermediate layer which is built up in such a way that the oxidation products of the developers are unable to diffuse into the layer containing the color couplers. For this purpose, compounds of the kind which react with the developer oxidation products to form colorless compounds are incorporated inter alia into this layer. These so-called white couplers only reduce the color fog to an extent that is inadequate for practical purposes.

Accordingly an object of the invention is to provide new anti-color-fogging agents which do not have any of the disadvantages referred to above, in particular can readily be synthesized and do not crystallize'out from their dispersions in aqueous hydrophilic colloid coating compositions before, during or after application, and, even during development,are not oxidized into colored secondary products.

It has now been found thatcolor fogging or discoloration of color photographic materials can be reduced by processing color photographic materials in the presence of 2-propinylthio derivatives.

Compounds corresponding to the following general formula represent particularly suitable 2-propynylthio derivatives for the purpose of the invention:

R-S-CH -C C-R in which R represents alkyl preferably with up to 18 carbon atoms, aryl e.g. phenyl or a heterocyclic radical, for excapto, amino, carboxy, sulfo, sulfamoyl, pyridyl, propymylthio, alkylthio which in turn can be substituted, e.g. with those mentioned above.

The compounds listed in thefollowing Tables have proved to be particularly suitable:

advantage of these compounds is that some of them are Table I not sufficiently resistant to diffusion, with the result that, in multilayer color photographic recording mate- RI S CH C 5 CH rials, they are able to migrate between the individual Compound 1 Melting or decompnsitiun layers, resulting in undesirable side effects. Some of the point compounds referred to above crystallize out during or 1 C H on a K 17 after their appllcatlon, or adversely affect physical or 1 Oil chemical properties of the layers, one particular disad- :g v vantage being that some alkyl hydroquinones form 001- 5 C::H;;: 0i] ored secondary products during coating or develop -gm::m ment as the result of an oxidation reaction. These trou- Table 2 x R H \l-S(H. ,C 501 N N Melting or decomposition (nmpountl No, X R: point x s sH 114-115 s S(,H,, 011

Table 4 -Continued Compound No. R

COOH

oil

w. l 8 H H m 0 0 mm HN O I \IHN H H S o w o l m m C C u m w. w

NHN

Table 4 COntinued Compound No. R' Melting or decomposition point N 47 CH 141 51 C..H-S \N 11 1.5

56 HN N Table 5 N N T T T \N HCECCH- .S-.----N f| l1 -S-CH CECH I a-I R-l Compound N01 X R Melting 0r decomposition point Table 5 Continued N N f/ X HCECCH -S-.N lr.-SCH ECH 1 R Compound No. X R Melting or decomposition point 5s CH SCH. .SCH. 300" s9 C 1K The compounds according to the invention are particularly suitable for reducing the formation of a color fog or discoloration in the color photographic materials.

The compounds according to the invention can be used with advantage anywhere where it appears advisable to eliminate undesirable oxidation products of the color developer.

The anti-color fogging agents according to the invention convert the oxidized form of any primary aromatic amine color developer (used for color developer) into the developer compound or into a form which does not couple with the color coupler.

. The compounds according to the invention are best added as anti-discolorants to any layer of any multilayer color photographic material. For example, they can be added to one or more of the photosensitive layers and/or to imtermediate or protective layers applied to or between the photosensitive layers. They can be used in color photographic materials which contain color couplers incorporated into the photosensitive emulsion layer, or in multilayer color photographic materials which do not contain any incorporated color couplers. The color photographic materials can be recording materials, copying materials or reverse materials. They can also be incorporated in diffusion-resistant form in separating layers of multilayer color materials and, in this way, can contribute towards better color separation so that oxidized colour developer is prevented from passing from one to the other layer.

Added to the color couplers as diffusion-resistant compounds, they serve to control the gradation of the silver halide layers. They can also be used as non-diffusion-resistant compounds in the photosensitive layers,

the adjacent layers and in the photographic processing baths, for example in stopping baths, fixing baths, hardening baths or simply in aqueous solution and as rinsing solutions during or after the photographic processing in order to prevent color fogging.

As already mentioned, the compounds can be introduced into the photographic materials at any time before chromogenic development of a silver image, or alternatively they can be added to a bath which follows to the development step to inhibit the formation of color fogs produced by unremoved residual color developers with residual color couplers.

The compounds according to the invention are prepared by known processes, for example according to the process described in German Patent 946,143, by reacting the mercapto or thione derivatives with chloro or bromopropine, preferably in a alkyline medium. The preparation of the compounds according to the invention is illustrated in the following examples. The rest of the compounds according to the invention can be similarly obtained. In the infra-red spectrum, the compounds according to the invention all show the characteristic E CH-valency frequency at 3,300 cm which, according to substitution, can be slightly shifted and more or less clearly pronounced.

PREPARATION OF COMPOUND 7 ether distilled off. Yield: 25 g; melting point: 34C; infra-red band at 3,300 cm.

PREPARATION OF COMPOUND 24 12.6 g (0.2 mol of sodium 2- mercaptobenzimidazole-o-sulfonic acid are dissolved at C in 50 ml of 1 n sodium hydroxide in the presence of 50 ml of alcohol and 0.75 g of sodium iodide. Following the addition of-a solution of 7.4 ml of 3- chloro-l-propine in 40 mlof ethanol, the mixture is heated under reflux for 30 minutes and acidified with hydrochloric acid after cooling. The oily product precipitated is purified by stirring with ether. Yield: 5 g; decomposition point: 305C; infra-red band at 3,300 cm.

PREPARATION OF COMPOUND 27 A solution of 14.8 ml of 3-chloro-1-propine in 40 m1 of methanol is added dropwise with stirring under nitrogen at room temperature to a suspension of 30 g (0.2 mol) of 2-mereaptobenzimidazole in 20 ml of 10 n sodium hydroxide and ml of methanol. After stirring for 1.5 hours, the suspension is concentrated in vacuo. The residue is purified by recrystallization from chloroform. Yield: 24 g; melting point: 160C; infra-red band at 3,300 cm.

PREPARATION OF COMPOUND 33 15 g (0. 1 mol) of thiomalic acid are dissolved at 80C in 60 ml of 5 n sodium hydroxide in the presence of 50 ml of ethanol and 1.5 g of sodium iodide. Following the addition of a solution of 14.8 ml of 3-chloro-1-propine in 30 ml of ethanol, the mixture is heated under reflux for 30 minutes and, after cooling, acidified with hydrochloric acid. The product is extracted with ether. The ethereal solution is washed, dried and the ether distilled off. The greasy residue is purified by dissolution in and reprecipitation from ether. Yield: 12.3 g; melting point: 1 1 1 1 12C; infra-red band at 2,270 cm.

PREPARATION OF COMPOUND 36 42.7 g (0.3 mol) of 2-mercaptohydroquinone are dissolved under nitrogen in 350 ml of dried acetonitrile and, following the addition of 24.6 g of anhydrous sodium acetate, a solution of 35.7 g of 3-bromo-1- propine in 50 ml of dried acetonitrile is added dropwise at 15to 20C. After heating under reflux for 2 hours and cooling, the salt precipitated is filtered off and the filtrate concentrated in vacuo. The crude product is purified by dissolution in and reprecipitation from chloroform. Yield: 23 g; melting point: 80 82C.

PREPARATION OF COMPOUND 43 A solution of 7.4 ml of 3-chloro-l-propine in 15 ml of ethanol is added dropwise with stirring to a suspension of 17.8 g (0.1 mol) of 3-mercapto-l-phenyl-l,2,4- triazole, in 20 ml of N sodium hydroxide and 100 ml of ethanol, the temperature rising to around 28C. After stirring for 14 hours at room temperature, the salt precipitated is filtered off and the filtrate concentrated in vacuo. The crude product is purified by repeated dissolution in and reprecipitation from ether. Yield: 14 g; melting point: 66 67C; infra-red band at 3,300

The compounds according to the invention can be added to the photographic emulsion or auxiliary layers, if any, at any time. The compounds used according to the'invention can be used in different concentrations according to the photosensitive silver halide emulsion used in each case, the concentration of silver halide in the emulsion layers and the concentration of dye to be formed. In cases where the compounds are used in the photographic material, for example in the silver halide emulsionlayers, it is best to use from 0.0001 to 0.01 mol'of compound per mol of silver halogenide, and preferably'0.002 mol per mol of silver halogenide. In cases'j'wh'ere the compounds are introduced into the color photographic materials in the form of a solution, for example in the form of a processing solution, it is best to use concentrations of about mg to 10 g per liter of solution and, preferably, concentrations of 100 mg to' l g per liter of solution. The optimum concentration is governed by the particular photographic recording material in which the anti-color-fogging agent is to be used, and can readily be determined by known methods.

The compounds according to the invention are preferably added in dissolved form to the auxiliary layers or to the photosensitive layer. Water, lower aliphatic alcohols, tetrahydrofuran, acetone, ethylacetate, dimethylformamide or mixtures thereof, are used as solvents. One preferred method of introduction is to dissolve the compounds according to the invention together with the color coupler and to introduce the resulting solution into the photosensitive silver halide layer. The compounds according to the invention are preferably introduced into the photosensitive emulsion after chemical ripening or before casting of the finished emulsion.

The usual silver halide emulsions are suitable for the color photographic materials which are used in accor dance with the invention. They can contain, as silver halide, silver chloride, silver bromide or mixtures thereof, which may additionally contain a small proportion of silver iodide of up to 10 mol percent.

Gelatin is preferably used as binder for the photographic layers. However, it can be replaced either wholly or in part by other natural or synthetic binders. Examples of suitable natural binders include alginic acid and derivatives thereof, such as salts, esters or amides, cellulose derivatives such as carboxymethyl cellulose, alkyl cellulose, such as hydroxyethyl cellulose, starch or derivatives thereof, such as ethers or esters of carragenates. The following are mentioned as examples of suitable synthetic binders: polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, and polyvinyl pyrrolidone.

The emulsions can also be chemically sensitized, for example by the addition during chemical ripening of sulfurcontaining compounds, for example allylisothiocyanate, allylthiourea, or sodiumthiosulfate. Other suitable chemical sensitisers include reducing agents, for example the tin compounds described in Belgian Pat. No. 493,464 and 568,687, also polyamines such as diethylene triamine, or aminomethylsulfinic acid derivatives, for example according to Belgian Pat. No. 547,323.

Noble metals and noble metal compounds, such as gold, platinum, palladium iridium, ruthenium or rhodium, also represent suitable chemical sensitizers. This method of chemical sensitization is described in the article by R. Koslowsky, in Z. wiss. Phot. 46, 6572 1951 v The emulsions can also be sensitized with polyalkylene oxide derivatives, for example with polyethylene oxide having a molecular weight of from 1,000 to 20,000, and also with condenzation products of alkylene oxides and aliphatic alcohols, glycols, cyclic dehydration products of hexitols, with alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides. The condenzation products have a molecular weight of at least 700, preferably of more than 1,000. In order to obtain special effects, these sensitizers can of course be used in combination, as described in Belgian Pat. No. 537,278 and in British Pat. No. 727,982.

The emulsions can also be optically sensitized, for example with the usual polymethine dyes such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styryl dyes, or oxanols. Sensitizers of this kind are described in The Cyanine Dyes and Related Compounds F.M. Hamer, (Interscience Publishers).

The emulsions can contain the usual stabilizers, such as, for example, homopolar or salt-like compounds of mercury with aromatic or heterocyclic rings, such as mercapto tetrazoles, simple mercury salts, sulfoniummercury double salts and other mercury compounds. Other suitable stabilizers include azaindenes, preferably tetraor penta-azaindenes, especially those substituted by hydroxyl or amino groups. Compounds of this kind are described by Birr in 7.. wiss, Phot. 47, 2 58 1952). Other suitable sensitizers include inter alia heterocyclic mercapto compounds, for example phenylmercaptotetrazole. quaternary benzthiazole derivatives or benztriazole.

The emulsions can be hardened in the usual way. for example with formaldehyde or halogen-substituted al dehydes containing a carboxyl, group, such as mucombromic acid, methane sulfonic acid esters ordialdehydes.

The emulsions can also contain increasing compounds, plasticizers and coating aids.

Photographic materials comprising a substrate and, applied one above the other to this substrate, photosensitive silver halide emulsion layers which are sensitive to red, green and blue light, are known to be particularly suitable for the production of multicolored. images. Silver images can be developed in layers of this kind and dyes produced image-wise in relation to the developed silver images. It is preferred to produce cyan magenta and yellow dyes. lt is preferred to produce dye images which are in a complementary relationship to that region of the spectrum to which the silver halide emulsion layer is sensitized.

Examples of photographic materials suitable for use according to the invention include recording copying and reverse materials, reprotechnical films or color photographic materials of the kind used, for example, in the dye diffusion process.

Suitable substrates for the color photographic materials according to the invention include the usual transparent substrates such as, for. example,. filmsof cellulose esters, polycarbonates, especially those based on bis-hydroxyphenyl alkanes, polyesters, especially polyethylene terephthalate and papers such as, for example, baryta paper substrates or papers coated with polyolefins, for example papers coated with polyethylene or polypropylene, which can beiirradiated with electrons other sensitivityto improve adhesion of the emulsion. It is of course also;

possible to use glass as substrate.

compounds of the para-phenylenediamine .type containing at least one primary amino group, are'used for producingthe dye images in the photographic materials according to the invention. Examplesof suitable color. N,N-dimethyl .-p-phenylene .di-'

developers include amine, N,N-diethyl-p-phenylenediamine, monomethylp-phenylenediamine, 2-amino-5-diethylamino toluene, N-butyl-N-w-sulfobutyl-p-phenylenediamine and 2- amino'-5-( N-ethyl-N-[3-methanesulfonamidoethylamino)-toluene. Other suitable color developers are described for example in J. Amer. Chem; Soc. 73, 3000 to 3025 (1951 The materials according to the invention can contain color couplers, masking and white couplers differing widely in their constitution which can be incorporated in diffusion-resistant form into hydrophilic binder layers, i.e., for example into a photosensitive silver halide emulsion layer or even into an adjacent nonphotosensitive binder layer. Provided that they are soluble in water, the color couplers can be added in the form of alkali salts in aqueous or aqueous-alcoholic solution. Water-insoluble couplers can be dispersed by known methods, for example using ethylacetate and a wetting agent, and incorporated into the emulsion in the form of a dispersion. If the coupler shows a tendency to recrystallize in the dispersion, it is possible ad ditionally to use an oilformer, for example dibutylphthalate. In addition, it is possible to use couplers which are not resistant to diffusion and which can'either be incorporated into the hydrophilic layers by means of mordants or incorporated by means of a color developer solution giving a conventional photographic reversal process, as described in US. Pat. No. 2,252,718. I Compounds derived from phenol or a-naphthol are used as cyan couplers, compounds derived from 2- pyrazolin-S-one or indazolone as magenta couplers and compounds derived fromB-ketocarboxylie acid derivatives, for example from benzoyl acetariilide, as yellow couplers. lt is possible to use couplers of the kind whose coupling position is notsubstituted, and also couplers of the kind which, in the coupling position, contain a substituent which is eliminated during the reaction with the developer oxidation products, for example accompanied by the liberation of a development inhibitor. Suitable color couplers are described in Farbkuppler by W. Pelz in Mitteilungen aus den Forschungsl'aborato'rien der Agfa Leverkusen-Munehen,

Vol. '3,page lll.

EXAMPLE l ing to the formula in aqueous-methanolic sodium hydroxide solution were added to 1 kg of a silver iodobromide emulsion containing 0.24 mol of silver salt (consisting of silver bromide with a silver iodide content of 1 mol percent). ,The pH-value of the emulsion was then adjusted to 6.4, followed by the addition of l g of saponin,.dissolved in water, aswetting agent, of 0.5 g of 4-hydroxy-6-methyll,2,3a,7-tetraazaindene in aqueous-alkaline solution as stabilizer and of l g of triaerylformal in methanolic solution as hardener, The emulsion thus obtained is di vided into 12 equal parts and the compounds according to the invention as set out in Table 6 below added to the individual samples in the quantities specified.

HOOC

Table 6 Sample Compound mg/kg of emulsion 1 no addition 2 l5 5 3 l5 15 Q 4 v 15 45 5 l7 l0 6 27 10 7 28 l() 8 42 l() 9 43 10 l() 47 10 5 1 1 53 20 12 54 2O Emulsion samples l to 10 were cast onto coronairradiated polyethylene-coated paper with a silver halide coating of 5 m Mol/m A 2 7( gelatin solution was applied as protective layer to each of the emulsion layv 5 g of N-b'utyl-N-w-sulfobutyl-p-phenylenediamine.'

1.2 g of hydroxylaminohydrochloride,

2 g of sodium sulfite sicc. 2 g of sodium metaphosphate, 75 g of potassium carbonate 1 g of potassium bromide made up with water to 1 liter.

Further processing comprises treatment in the following baths:

Stopping bath: a buffer solution of sodium acetate and acetic acid adjusted to pH 6.5. Bleach-fixing bath: 10 g of the sodium salt of ethylene diamine tetraacetic acid, 2 g of sodium sulfite sicc, 40 g of the sodium-iron(lll) salt of ethylene diamine tetraacetic acid, 13 g of disodium phosphate, 100 g of ammonium thiosulfate, made up with water to 1 liter and adjusted to pH 7.0.

The processing times after development were as follows: 1 minute in the stopping bath, 1 minutes rinsing, 5 minutes in the bleach-fixing bath, minute s rinsing.

Yellow images of the step wedges l to 10 are obtained.

The results of sensitometric evaluation of the samples thus obtained are set out in Table 7 below:

As can be seen from Table 7, addition of the compounds according to the invention produces a reduction in minimum density, compared with sample 1 which does not contain a compound according to the invention, without affecting gradation, maximum density or sensitivity of the samples.

Another strip of each of samples 1 to 12 was developed for 15 minutes at C without exposure and then 16 7 further processed as described above. The minimum densities of the sensitometer strips thus obtained are shown in Table 8 below:

Table 8 Sample Minimum density at 3 times the developing time 0. l 8 0. 14 0.12 0. l l 0.08 0.09 0.10 0.09 0.1 l 0. 12 0.08 0.08

As can be seen from the Table, prolonged development in the case of sample 1 which does not contain a compound according to the invention, considerably increases color fogging. By contrast, the minimum density of samples 2 to 12 according to the invention is considerably lower than that of comparision sample 1 at 3 times the developing time.

Table 9 Dispersion mg/l0 g of colour coupler Compound l5 l5 l5 17 27 28 no addition Table 9-Continued l Dispersion mg/ 10 g of colour coupler Compound Preparation of the coupler dispersion: v

10 g of color coupler are dissolved in 10 g of dibutylphthalate, 20 g of butyl acetate, 2 g of sodium dodeeylbenzene sulfonate and the resulting solution was emulsified at 40C into 300 g of a 10 percent gelati'n sothe emulsion in a I Table 10.

Dispersion Sensitivity (iradation Maxi- Minimum mum 1 lg of l X t] density density Similar samples containing dispersions l to 10 were developed for 15 minutes at C without exposure described in Example 1, and their minimum density determined.

Table l 1 Minimum density at 3 times the developing time Dispersion EXAMPLE 3 A color photographic multilayer material containing a blue-sensitized, a green-scnsitized and a redsensitized layer and a gelatin separating layer between the respective emulsion layers, was prepared on a corona-irradiated polyethylene-coated paper substrate, 300 mg of compound 17 in the form of a 1 percent ethanolic solution being added to the emulsions ready for casting for the blue-sensitive yellow layer, the green-- sensitive magenta layer and the red-sensitive cyan layer, per mol of silver halide present.

The color photographic multilayer material thus prepared was exposed in'a conventional sensitometer behinda test image containing a test image containing a I grey, a blue, a green and a red step wedge.

A similar color photographic multilayer material was prepared for comparison purposes without any of the compounds according to the invention in the emulsions.

After exposure and processing as described in Example lycomparisori of the sensitometric results showed that the'color photographic multilayer material A, containing compound 17 according to the invention; and

comparison material B had the same sensitivity, the same gradation and same saem maximum density.

Comparison of the minimum densities is shown in Table l 2 below.

" Table 12 Minimum density Sample A yellow purple bluegreen A I 0.10 0.11 v 0.10 B 0.l4 0.13 I, 0.10

EXAMPLE 4 Table 13 Minimum density Sample yellow purple blue-green EXAMPLE 5 A color photographic multilayer material on a baryta paper substrate was processed without exposure in the same way described in Example 1, except that treatment in the bleach-fixing bath was followed by rinsing for only 3 minutes instead of 10 minutes.

The color photographic material was then divided and one half, hereinafter referred to as sample D, was immersed for 1 minute in a buffer solution of sodium acetate and acetic acid with a pH-value of 6.5. The other half, hereinafter referred to as sample E, was immersed in the same buffer solution additionally containing l g of compound 32 per liter.

After drying in air. sample E which had been immersed in a buffer bath containing compound 32 according to the invention gave a 0.02 lower fogging value than comparison sample D in whose case color developer residues left in the material formed a dye with residual color components on drying in air. This reaction was inhibited in the sample according to the invention through the addition of compound 32.

We claim:

1. A process for the production of colored images by chromogenic processing of color photographic material having at least one light sensitive silver halide emulsion layer by imagewise exposure and processing in color photographic processing bath comprising color developingwith a color developer and color coupler and said process including processing in the presence of a stabilizing agent wherein the improvement comprises processing the exposed photographic material in the presence of a stabilizing amount of a 2- propynylthio derivative of the formula in which R represents an alkyl, aryl or heterocyclic group selected from the group consisting of imidazole, oxazole, thiazole, triazole, tetrazole, oxdiazole, thiadiazole, benzimidazole, benzoxazole, benzthiazole, pyridine, pyrimidine, triazine, quinoline, quinazoline, purine,s-triazolo-[4,3-a]-quinoline and R represents hydrogen, sodium or potassium.

2. A process according to claim 1 wherein R represents alkyl containing up to l8 carbon atoms, l,3,4- thiadiazole, 1,2,4-triazole, a benzothiazole, a benzimidazole or a carboxyphenyl group.

3. A process according to claim 1 wherein the 2- propynylthio derivative is present in the color photographic material.

4. A process according to claim 1 wherein the 2- propinylthio derivative used is present in a photographic processing bath.

5. A process according to claim 4 wherein the processing bath used is a stopping bath, fixing bath, hardening bath or a rinsing bath.

6. A light sensitive color photographic material comprising at least one silver halide emulsion layer and a stabilizing agent the improvement according to which the stabilizing agent capable of stabilizing a color photographic material against the formation of color fog is a 2-propynylthio derivative of the formula R represents an alkyl, aryl or heterocyclic group selected from the group consisting of imidazole, oxazole, thiazole, triazole, tetrazole, oxdiazole, thiadiazole, benzimidazole, benzoxazole, benzthiazole, pyridine, pyrimidine, triazine, quinoline, quinazoline, purine, s-triazolo-[4,3-a]-quinolinc and R represents hydrogen, sodium or potassium.

7. A light sensitive color photographic material according to claim 6 wherein R represents alkyl containing up to 18 carbon atoms, a carboxy phenyl group, or a 1,3,4-thiadiazole, a 1,2,4-triazole, a benzothiazole or benzimidazole group.

UNITED STATES PATENT AND TRADEMARK OFFICE CE TEHQATE 0% C0 ECTION 5 PATENT NO. 3,910,790 p DATED 3 OCTOBER 7, 1975 age 1 of 2 tNVENTOR(S) Karl Lohmer et: al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lines 45 and 46, "propymylthio" should read propynylthio Column 5 compound 40, should read as follows Column 7, compound 47, should read as follows mn 7, compound 50, should read as follows N HCEC-CHZ-S \'N o l HZN UNITED STATES PATENT AND TRADEMARK OFFICE CE'HHCATE r CEC'H PATENT NO. 1 3,91 Page 2 of 2 DATED rNvENT0R(s OCTOBER 7, 1975 Karl Lohmer et al.

It is certifiedthat error appears in the above-identifier] patent and that said Letters Patent are hereby corrected as shown below:

Column 8, the compound in the heading of Table 5 should read as follows:

N N N/\'-XK N HCECCH2-S- N NJLS-CHZ-CECH R R Column 8, compound 57, the radical should read as follows CH2-S-CH2 Column 9, the compound in the heading of Table 5-Continued should read as follows rated this igncd and twentieth Day of April1976 [SEAL] Attest:

RUTH C. MaSON C. MARSHALL DANN Arresting Officer Commissioner of Parents and Trademarks 

1. A PROCESS FOR THE PRODUCTION OF COLORED IMAGES BY CHROMOGENIC PROCESSING OF COLOR PHOTOGRAPHIC MATERIAL HAVING AT LEAST ONE LIGHT SENSITIVE SILVER HALIDE EMULSION LAYER BY IMAGEWISE EXPOSURE AND PROCESSING COLOR PHOTOGRAPHIC PROCESSING BATH COMPRISING COLOR DEVELOPING WITH A COLOR DEVELOPER AND COLOR AND SAID PROCESS INCLUDING PROCESSING IN THE PRESENCE OF A STABILIZING AGENT WHEREIN THE IMPROVEMENT COMPRISES PROCESSING THE EXPOSED PHOTOGRAPHIC MATERIAL IN THE PRESENCE OF A STABLIZING AMOUNT OF A 2-POLYNYTHIO DERIVATIVE OF THE FORMULA
 2. A process according to claim 1 wherein R1 represents alkyl containing up to 18 carbon atoms, 1,3,4-thiadiazole, 1,2,4-triazole, a benzothiazole, a benzimidazole or a carboxyphenyl group.
 3. A process according to claim 1 wherein the 2-propynylthio derivative is present in the color photographic material.
 4. A process according to claim 1 wherein the 2-propinylthio derivative used is present in a photographic processing bath.
 5. A process according to claim 4 wherein the processing bath used is a stopping bath, fixing bath, hardening bath or a rinsing bath.
 6. A light sensitive color photographic material comprising at least one silver halide emulsion layer and a stabilizing agent the improvement according to which the stabilizing agent capable of stabilizing a color photographic material against the formation of color fog is a 2-propynylthio derivative of the formula R1-S-CH2-C*C-R2 in which R1 represents an alkyl, aryl or heterocyclic group selected from the group consisting of imidazole, oxazole, thiazole, triazole, tetrazole, oxdiazole, thiadiazole, benzimidazole, benzoxazole, benzthiazole, pyridine, pyrimidine, triazine, quinoline, quinazoline, purine, s-triazolo-(4,3-a)-quinoline and R2 represents hydrogen, sodium or potassium.
 7. A light sensitive color photographic material according to claim 6 wherein R1 represents alkyl containing up to 18 carbon atoms, a carboxy phenyl group, or a 1,3,4-thiadiazole, a 1,2,4-triazole, a benzothiazole or benzimidazole group. 